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Can Haiti rebuild to save lives?

By Kenneth KiddFeature Writer

Sun., March 7, 2010

PORT-AU-PRINCE–Francis is standing on a ridge in the Canape Vert neighbourhood, overlooking the destruction in the valley below.

In the palm of his left hand, he has a kind of damp, white sludge, through which he's running the index finger of his right hand.

"They call it sand," says Francis, an engineer with an international aid group who, wanting to be as candid as possible, decides he doesn't want his last name used. "But it's not building sand."

It is, instead, not a lot more than limestone dust, which, when mixed with cement, is scarcely the ideal starting recipe for either mortar or concrete.

A few blocks away, Francis spies the result in action at a construction site started before the earthquake struck. He looks down at the "blinding," or ground-level foundation of a building, from which rise bare columns of metal reinforcing bars. The foundation, beyond the cement and limestone sludge, doesn't reveal any bigger pieces of aggregate or stone to give it heft. The entire structure will, as a result, be weaker from the outset.

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"If you start building a wall, it will not bind with the blinding."

It is, however, what you get when you combine poverty with the island's natural building materials, materials ill suited to constructing the kind of stable buildings that can resist and withstand even major earthquakes.

"They have no choice," says Francis. "You can't compare this place with places where they have proper stone and proper sand."

As University of Colorado seismologist Roger Bilham noted in a report soon after the earthquake in Haiti, "the buildings had been doomed during their construction."

THERE ARE PROVEN ways of constructing buildings in places, like Port-au-Prince, where earthquakes are likely. There is, after all, an engineering axiom that buildings kill people, not earthquakes.

But both gods and devils lurk in the details.

One of the most used and trusted methods is called "confined masonry construction" and, from a seismic engineering point of view, it has an elegant simplicity.

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Developed in the wake of the 1908 earthquake in Messina, Italy, that killed more than 70,000 people, the essential idea is to spread the loads and stresses over as great an area as possible, and to prevent even damaged walls from tumbling.

In standard construction using re-enforced concrete, it's the columns and beams and floors that bear the load. The stuff in between is infill, with no great structural value.

Confined masonry construction turns that on its head. Instead of building the beams and columns first, you build the masonry walls first. Then you build what the engineers like to call tie-beams and tie-columns around them, confining them more securely.

The practical result is that all the masonry walls are load-bearing, part of an integrated structure that transmits loads and stresses across the whole structure and down to the foundation. And because both the construction method and the distribution of load "confines" the masonry, even if it's damaged, it's far more likely to remain in place.

Little wonder this style of building has spread around the world, and proven itself able to withstand earthquakes, even in structures as tall as five storeys.

SUPERFICIALLY, at least, a lot of Haitian buildings look like they might have been built this way. In truth, relatively few actually were; those are the ones left standing, or having suffered comparatively little damage.

The rest, in various stages of collapse, reveal how, as seismologist Bilham put it in a recent report, "every possible mistake was evident."

The steel used in construction, for instance, was often brittle. Nor were the reinforcing bars inside tie-columns, tie-beams and floors woven together where they meet. That resulted in weakness precisely where the stresses during an earthquake can be greatest.

Even the concrete and mortar used in many structures was compromised from the outset. Even where there is aggregate or small rocks added to increase strength, it's often smooth and rounded limestone taken from river beds. Ideally, what you want is crushed, angular stone with sharp edges that help bind the concrete together, but as Francis notes, "It's easier to get it from the river."

Add in limestone sludge or, just as bad, dirty or salty sand from beaches and you're introducing a raft of additional weakness.

Dirty sand or water will make the concrete set faster, give it less time to cure and become as strong as possible. And the salt simply adds an element that's corrosive to the re-enforcing bars from the outset.

BUT EVEN BEYOND the historic impediments to building safe houses in Haiti, there is, perhaps more importantly, a conceptual one.

A good many Haitian homes have been built on land the occupants don't own, an elaborate kind of squatting. They never knew when they might have to pick up stakes.

"They were built to be moveable, easily de-constructible, which was important for people in a situation of economic vulnerability," says Melanie Newton, a University of Toronto historian who specializes in Caribbean affairs. "But, in an earthquake situation, it becomes a disaster."

It's also a legacy of the colonial and modern era, which may indirectly point the way to another way forward, or at least a temporary way forward.

Earthquakes and hurricanes had beset the island for millennia before Europeans arrived, and the indigenous population adapted accordingly. Their wooden huts with thatched roofs were designed, if not to withstand a natural disaster unscathed, then at least to minimize the danger.

In the early colonial period, when Haiti was a far more rural country, that gave rise to a familiar narrative whenever an earthquake struck. "All the European structures would collapse and the homes of the indigenous people would survive," says Newton.

She suspects that such native knowledge, applicable to earthquakes as much as hurricanes, could still be found as Haiti recovers from the recent destruction. But, in the rush to rebuild Haiti for the 21st century, she's not sure it would be heeded.

"I fear that there are all these vultures hovering around, the elites within Haiti and foreign contractors, who are waiting for these massive rebuilding contracts," says Newton.

"On paper, it will all look just great, but, in reality, it will not be attuned to people's actual needs. It will not be a project controlled or determined by the people who are actually going to live in those houses."

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